I've done the 20k twice. I am down to do the 10 this time with a couple of friends plus I've not been running so much recently and the 20k is quite challenging compared to a 10 or 15k.Trail running just pulls me in somehow. That looks awesome.
Have you done that race before? What distance are you aiming for.
I much prefer trail to road running. It works your body in different ways and I love being in the great outdoors with some dirt under my boots!